Method And Apparatus For Preparing Platelet Rich Plasma And Concentrates Thereof

ABSTRACT

The PRP separator-concentrator of this invention is suitable for office use or emergency use for trauma victims. The PRP separator comprises a motorized centrifugal separation assembly, and a concentrator assembly. The centrifugal separator assembly comprises a centrifugal drum separator that includes an erythrocyte capture module and a motor having a drive axis connected to the centrifugal drum separator. The concentrator assembly comprises a water-removal module for preparing PRP concentrate. The centrifugal drum separator has an erythrocyte trap. The water removal module can be a syringe device with water absorbing beads or it can be a pump-hollow fiber cartridge assembly. The hollow fibers are membranes with pores that allow the flow of water through the fiber membrane while excluding flow of clotting factors useful for sealing and adhering tissue and growth factors helpful for healing while avoiding activation of platelets and disruption of any trace erythrocytes present in the PRP.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/342,761 filed Jan. 30, 2006, which claims the benefit under 35 USC120 of the filing dates of Provisional Application No. 60/651,050 filedFeb. 7, 2005, Provisional Application No. 60/654,718 filed Feb. 17, 2005and Provisional Application No. 60/723,312 filed Oct. 4, 2005.

FIELD OF THE INVENTION

This invention relates to a device and method for preparingplatelet-plasma concentrates with improved wound healing properties foruse as a tissue sealant and adhesive. The product has a fully active(un-denatured) fibrinogen concentration that is several times greaterthan is found in blood and a platelet concentration that is many timesgreater than is found in blood.

BACKGROUND OF THE INVENTION

Blood can be fractionated, and the different fractions of the blood canbe used for different medical needs. Under the influence of gravity orcentrifugal force, blood spontaneously sediments into three layers. Atequilibrium, the top low-density layer is a straw-colored clear fluidcalled plasma. Plasma is a water solution of salts, metabolites,peptides, and many proteins ranging from small (insulin) to very large(complement components).

The bottom, high-density layer is a deep red viscous fluid comprisinganuclear red blood cells (erythrocytes) specialized for oxygentransport. The red color is imparted by a high concentration of chelatediron or heme that is responsible for the erythrocytes' high specificgravity. The relative volume of whole blood that consists oferythrocytes is called the hematocrit, and in normal human beings thiscan range from about 37% to about 52% of whole blood.

The intermediate layer is the smallest, appearing as a thin white bandabove the erythrocyte layer and below the plasma layer; this is calledthe buffy coat. The buffy coat itself has two major components,nucleated leukocytes (white blood cells) and anuclear smaller bodiescalled platelets (or thrombocytes). Leukocytes confer immunity andcontribute to debris scavenging. Platelets seal ruptures in bloodvessels to stop bleeding, and deliver growth and wound healing factorsto a wound site. Slower speed or shorter duration centrifugation permitsseparation of erythrocytes and leucocytes from plasma, while the smallerplatelets remain suspended in the plasma, resulting in PRP.

A major improvement in making plasma concentrate from whole blood foruse in wound healing and as a tissue sealant is described in U.S. Pat.No. 5,585,007; this patent is hereby incorporated by reference in itsentirety. This device, designed for placement in a medical laboratory orsurgical amphitheatre, used a disposable cartridge for preparing tissuesealant. The device was particularly applicable for stat preparations ofautologous tissue sealants. Preparation in the operating room of 5 ml ofsealant from 50 ml of patient blood required less than 15 minutes andonly one simple operator step. There was no risk of tracking errorbecause processing can be done in the operating room. Chemicals addedcould be limited to anticoagulant (e.g., citrate) and calcium chloride.The disposable cartridge could fit in the palm of the hand and washermetically sealed to eliminate possible exposure to patient blood andensure sterility. Adhesive and tensile strengths of the product werecomparable or superior to pooled blood fibrin sealants made withprecipitation methods. Use of antifibrinolytic agents (such asaprotinin) was not necessary because the tissue sealant contained highconcentrations of natural inhibitors of fibrinolysis from the patient'sblood. This new tissue sealant also optionally contained patientplatelets and additional factors that promote wound healing, healingfactors that are not present in commercially available fibrin sealants.

This device used a new sterile disposable cartridge with the separationchambers for each run. Since the device was designed to be used in anormal medical setting with ample power, the permanent components,designed for long-term durability, safety and reliability, wererelatively heavy, using conventional centrifuge motors and accessories.

Small, self-contained centrifugal devices for obtaining plateletconcentrates from blood are described in commonly assigned, copendingapplication Ser. No. 10/394,828 filed Mar. 21, 2003, the entire contentsof which are hereby incorporated by reference. This device separatesblood into erythrocyte, plasma and platelet layers and selectivelyremoves the platelet layer as a platelet concentrate, that is, plateletssuspended in plasma. The plasma fraction, being in an unconcentratedform, is not effective as a hemostat or tissue adhesive.

SUMMARY OF THE INVENTION

It is an objective of this invention to provide a compact,self-contained system for producing a concentrate of platelets suspendedin concentrated fully active plasma, that is substantially unactivatedplatelets suspended in plasma concentrated by removing water, leavingthe fibrinogen in a fully active form.

The PRP separator-concentrator of the present invention is suitable foroffice use or emergency use for trauma victims.

One embodiment is a disposable self-contained PRP separator andconcentrator unit designed for use with a permanent motor assembly.

Another embodiment is a self-contained disposable PRP separator andconcentrator that includes an internal motor and power supply assembly.

A still further embodiment comprises a motorized centrifugal separationunit for preparing PRP.

The PRP separator comprises a motorized centrifugal separation assemblyfor and an optional concentrator assembly for concentrating the PRP. Thecentrifugal separator assembly comprises a centrifugal drum separatorthat includes an erythrocyte capture module and a motor with a driveaxis connected to the centrifugal drum separator. The concentratorassembly comprises a water-removal system for preparing PRP concentrate.

The centrifugal drum can have an inner wall surface with an upper edgeand a lower edge, a drum bottom, and a central axis; the drum bottom canhave a central depression and a floor sloping downward from the loweredge to the center of the central depression.

In the portable, self-contained embodiment of the PRPseparator-concentrator of this invention, the motorized centrifugalseparation assembly includes a motor having a drive axis, the drive axisbeing coaxial with the central axis. The motor can have the capacity torotate the centrifugal drum at a speed of at least 2,000 rpm for 120seconds. The battery can be connected to the motor through an on/offswitch or timer switch, the battery having the capacity to providesufficient power to complete the separation process. The portablecentrifugal separator can be fully enclosed within an outer container,the outer container having a top with a sterile syringe port alignedwith the central depression, and an access tube connected to andextending downward from the syringe port.

In one embodiment, the erythrocyte capture module is a depth filterlining the inner wall surface of the centrifugal separator unit, thedepth filter having pores sized to capture erythrocytes moving into thepores during centrifugal separation of the erythrocytes from blood andto retain the erythrocytes in the depth filter when centrifugalseparation is completed. The term “depth filter”, as used herein, isdefined as a filter medium that retains contaminants primarily withintortuous passages. It can include an open-cell foam or other matrix madeof a material such as a felt that does not significantly activateplatelets contacting the surface thereof, whereby erythrocytes movingoutward through the plasma during centrifugation move into and arecaptured by the depth filter leaving behind PRP substantially free fromerythrocytes.

In an alternative embodiment of the invention, the inner wall surface ofthe centrifugal drum can be sloped outwardly from the bottom at an angleof from 1° to 15° with respect to the central axis. The upper edge ofthe centrifugal drum can be surrounded by an outer, annular erythrocytecapture chamber, the erythrocyte capture chamber including, an outerwall and an inner wall, the outer wall having an upper edge with anelevation higher than the inner wall. The volume of the erythrocytecapture chamber below the top of the inner wall is sized to retain thetotal volume of separated erythrocytes in the blood while retaining aminimal volume of the PRP. In this embodiment, erythrocytes movingoutward through the plasma during centrifugation are retained againstthe outer wall of the erythrocyte capture chamber and slide downward tosubstantially fill the lower volume of the erythrocyte capture chamberwhen centrifugation is ended. During centrifugation, platelets suspendedin the liquid in the erythrocyte capture chamber are carried with theflow of plasma displaced by sedimenting erythrocytes so that they travelto the top and over the inner surface of the erythrocyte capture chamberand into the centrifugal drum. Optionally, at least the upper surface ofthe inner wall of the erythrocyte capture chamber has a slope forming anangle “a” of at least 25° with respect to the central axis forfacilitating flow of platelets against the centrifugal force up and overthe upper edge of the erythrocyte capture chamber during centrifugation.As the plasma flows from the erythrocyte capture chamber to thecentrifugal chamber, the portal or cross-sectional area through whichthe plasma flows is reduced by the rising slope of the inner wallsurface, causing an increase in the plasma flow velocity over thesurface and increasing the portion of platelets successfully transportedby the plasma.

In one embodiment, the concentrator assembly of the PRPseparator-concentrator includes a water-removing hollow fiber cartridge,a pump, and tubing connecting with the hollow fiber cartridge and thepump that circulates PRP in the centrifugal drum through the pump andhollow fiber cartridge and then returns it to the centrifugal drum. Inthe hollow fiber cartridge, the fibers are ultrafiltration membraneswith pores that allow the flow of water through the fiber membrane whileexcluding the passage of growth factors helpful for healing. The porestructure and surfaces are selected to avoid activation of platelets anddisruption of any erythrocytes remaining in the PRP.

In another embodiment, the concentrator assembly includes a plasmaconcentrating syringe, the syringe having a Luer coupling for connectionto the access tube to the center or central depression of thecentrifugal drum. In this embodiment, the plasma concentrating syringecomprises a cylindrical barrel with an inner surface and an inlet/outletport, and a cylindrical actuated piston having an outer surface engagingthe inner surface of the barrel. Concentrating beads which can bedesiccated hydrogel are positioned between the piston and theinlet/outlet port. A filter is positioned adjacent the inlet/outlet portto prevent escape of the concentrating beads through the inlet/out port.In the operation of the syringe concentrator, movement of the piston ina direction away from the inlet/outlet port draws PRP into theconcentrating chamber. Water is removed from the PRP by theconcentrating beads, thereby concentrating the PRP without activatingthe platelets or denaturing the fibrinogen in the plasma. Movement ofthe piston toward the inlet/outlet port expels concentrated PRP throughthe inlet/outlet port.

Because the devices of this invention can be operated with standardbatteries as their power source, they consume far less power than priorart centrifuge devices, leading to substantial power saving.

A further PRP separator and concentrator embodiment of this inventionhas a central axis comprises a stationary housing and a rotary assemblymounted for rotation about the central axis with respect to thestationary housing. The rotatable assembly comprises a rotatablecentrifugal separator and concentrator and a drive motor. A couplingconnects the drive motor and the rotatable assembly, the motor and drivecoupling being positioned to rotate the rotatable assembly about thecentral axis.

The centrifugal separator has an inner separation chamber and an outererythrocyte capture system. The concentrator comprises a concentrationchamber containing desiccated beads. The concentration chamber comprisesa floor and a plurality of upright screen supports, the upright screensupports having an inner surface and an outer surface. A cylindricalscreen is supported on the outer surface of the upright screen supports.

An axially concentric stationary tube is secured to the housing andextends through the concentration chamber. A stationary bead rake issecured to the tube and extends radially outward. The rake has a distaledge that is positioned adjacent the inner surface of the upright screensupports,

With this assemblage, slow rotation of the rotary assembly with respectto the stationary housing pulls the beads past the stationary rake,reducing gel polarization and clumping of the beads.

Each pair of adjacent upright screen supports can define a desiccatingbead receptor for holding desiccated beads radially outward from thedistal edge of the rake, whereby bead disruption by the rake during highspeed rotational phases is substantially avoided.

The separator and concentrator can include a motor controller, whereinthe drive motor has a high rotational speed required for centrifugalseparation and PRP collection phases and a slow rotational speedrequired for water removal by desiccated beads, the motor controllerinclude a switch for initiating high and low rotational speeds of therotary assembly.

The switch initiates high rotational speed of the rotary assembly duringcentrifugal and PRP concentrate collection phases and initiates low slowrotational speed of the rotary assembly during the PRP concentratecollection phase.

Another rotatable PRP concentrator of this invention has a stationaryhousing with a central axis, the concentrator including a drive motorand a coupling connecting the drive motor and the centrifugal separatorfor rotation about its central axis. The concentrator comprises aconcentration chamber containing desiccated beads, the concentrationchamber comprising a floor and a plurality of upright screen supports.The upright screen supports have an inner surface and an outer surface.A cylindrical screen is supported on the outer surface of the uprightscreen supports. An axially concentric stationary tube secured to thehousing extends through the concentration chamber. A stationary beadrake is secured to the tube and extends radially outward to adjacent theinner surface of the upright screen supports.

With this configuration, slow rotation of the rotary assembly withrespect to the stationary housing pulls the beads past the stationaryrake, reducing gel polarization and clumping of the beads.

Each pair of adjacent upright screen supports and the screen segmentsextending therebetween defines a desiccating bead receptor for holdingdesiccated beads radially outward from the distal edge of the rake,whereby bead disruption by the rake during high speed rotational phasesis substantially avoided.

The separator and concentrator can include a motor controller, whereinthe drive motor has a high rotational speed required for the PRPcollection phase and a slow rotational speed required for water removalby desiccated beads. The motor controller includes a switch forinitiating high and low rotational speeds of the rotary assembly. Theswitch initiates high rotational speed of the rotary assembly during thePRP concentrate collection phase and initiates low slow rotational speedof the rotary assembly during the PRP concentrate collection phase.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered with the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional drawing of a centrifugal separatorof this invention with an annular erythrocyte trap.

FIG. 2 is a fragmentary cross-sectional drawing of the centrifugalseparator and annular erythrocyte trap portion of the centrifugalseparator shown in FIG. 1.

FIG. 2A is a fragmentary cross-sectional drawing of an alternativeerythrocyte trap.

FIG. 2B is a detailed fragmentary view of a vent system according tothis invention that uses a sterile porous sheet to allow air movementinto and from the outer container.

FIG. 2C is a detailed fragmentary view of a vent system according tothis invention that uses a flexible balloon or diaphragm to allow airmovement into and from the outer container.

FIG. 3 is a schematic cross-sectional drawing of the separationseparator of FIG. 1 after being loaded with blood.

FIG. 4 is a schematic cross-sectional drawing of the separationseparator of FIG. 1 during the spin separation phase.

FIG. 5 is a schematic cross-sectional drawing of the separationseparator of FIG. 1 after centrifugation has ended.

FIG. 6 is a cross-sectional drawing of a concentrator syringe.

FIG. 7 a schematic cross-sectional drawing of the separation separatorof FIG. 1 after PRP has been drawn into a concentrator syringe.

FIG. 8 shows a concentrator syringe containing PRP after the waterremoval phase with the PRP concentrate ready for use.

FIG. 9 is a schematic cross-sectional drawing of a separation separatorof this invention with a depth filter erythrocyte trap.

FIG. 10 is a schematic cross-sectional drawing of the separationseparator of FIG. 9 after being loaded with blood.

FIG. 11 is a schematic cross-sectional drawing of the separationseparator of FIG. 10 during the spin separation phase.

FIG. 12 is a schematic cross-sectional drawing of the separationseparator of FIG. 10 after centrifugation has ended.

FIG. 13 is a schematic cross-sectional drawing of the separationseparator of FIG. 9 after PRP has been drawn into a concentratorsyringe.

FIG. 14 is a schematic representation of a combination centrifugalseparator and hollow fiber concentrator of this invention.

FIG. 15 is a schematic cross-sectional view of a hollow fiberconcentrator according to this invention.

FIG. 16 is a cross-sectional view of the hollow fiber concentrator ofFIG. 15, taken along the line 16-16.

FIG. 17 is a schematic cross-sectional view of the membrane valve in thehollow fiber concentrator of FIG. 15.

FIG. 18 is a schematic cross-sectional drawing of an automatedspring-clutch system for preparing PRP concentrate from a patient'sblood.

FIG. 19 is an isometric view of a plasma separator and concentratorembodiment of this invention.

FIG. 20 is a top view of the plasma separator and concentrator shown inFIG. 19.

FIG. 21 is a cross-sectional view of the plasma separator andconcentrator of FIG. 20, taken along the line 21-21, exploded along thevertical axis to show the motor drive and drive receptor relationshipprior to placing the disposable separator-concentrator assembly on thedrive base.

FIG. 22 is a cross-sectional view of the plasma separator andconcentrator of FIG. 20, taken along the line 22-22.

FIG. 23 is a fragmentary cross-sectional view of theseparator-concentrator shown in FIG. 22.

FIG. 24 is a cross-sectional drawing of the device of FIGS. 19-23 afterblood has been added.

FIG. 25 is a cross-sectional drawing of the device of FIGS. 19-23 duringthe centrifugal separation stage producing PRP.

FIG. 26 is a cross-sectional drawing of the device of FIGS. 19-23 duringthe slow rotation concentration stage.

FIG. 27 is a cross-sectional drawing of the device of FIGS. 19-23 duringthe centrifugal PRP concentrate separation stage.

FIG. 28 is a cross-sectional view of a portable embodiment of thisinvention.

DETAILED DESCRIPTION OF THE INVENTION

This device and method separates plasma-rich plasma from blood andremoves water from the plasma-rich plasma without denaturing thefibrinogen or activating the platelets invention. One aspect of theinvention is a portable, completely self-contained device that performsthis method with a patient's blood to provide an autologous product thatis useful as wound healing tissue sealant and adhesive that promotes andspeeds healing. Another aspect of the invention is a portable disposablesystem that can be used with a permanent motorized unit to provide thismethod and product. A still further aspect is a portable disposablesystem for producing PRP from a patient's blood.

The devices of this invention are small, portable, self-contained,disposable PRP separation systems. The centrifugal separation modulesdescribed with respect to FIGS. 1-13 are one aspect of this invention.They are directed to disposable PRP separation systems that can be usedby a medical assistant or doctor without extensive training to preparePRP and a PRP concentrate from a patient's blood within minutes, with ahigh recovery of platelets and without significant activation of theplatelets. The devices are completely automated and require no userintervention between, first, loading and actuating the device and,second, retrieving the PRP. The devices are able to process bloods ofdifferent hematocrits and different plasma densities.

Another more highly automated separator-concentrator of this inventionis the combination centrifugal separator and hollow fiber cartridgeconcentrator shown in FIG. 14. This system requires no user interventionbetween loading the blood and retrieving PRP concentrate.

FIG. 1 is a schematic cross-sectional drawing of a centrifugal separatorof this invention with an annular erythrocyte trap, and FIG. 2 is afragmentary cross-sectional drawing of the centrifugal separator andannular erythrocyte trap shown in FIG. 1. Referring to FIGS. 1 and 2,the separation system comprises a centrifugal separator unit or chamber2 and a motor 4. The centrifugal separator unit comprises a centrifugaldrum 5 having an inner wall surface 6 with an upper edge 8 and a loweredge 10, a drum bottom 12, and a central axis (not shown). The drumbottom 12 has a central depression 14, the bottom 12 constituting afloor sloping downward from the lower edge 10 to the central depression14. The motor 4 has a drive axis 16 that is coaxial with the centralaxis. The motor 4 has the capacity to rotate the centrifugal drum at aspeed of at least 2,000 rpm for 120 seconds.

The complete, self-contained unit includes a battery 18 connected to themotor 4 through conventional power connections, the battery 18 havingsufficient capacity to complete the separation process. The battery 18is connected to the motor through an on/off time switch 20 with a manualknob 22.

An outer container 24 encloses the centrifugal separation unit. Thecontainer 24 has a top 26 with a sterile syringe port 28 that can be aLuer fitting aligned with the central depression 14. An access tube 29connects to and extends downward from the syringe port 28 into theseparation chamber 2. Tube 29 is used for introducing blood into theseparation chamber 2 and for removing PRP from the separation chamber 2as is explained in greater detail with respect to FIGS. 2-6 hereinafter.

The inner wall surface 6 of the centrifugal drum 5 is sloped outwardlyfrom the bottom 12 at an angle of from 75 to 89° from the central axis.The upper edge 8 of the centrifugal drum 5 is surrounded by an outer,annular erythrocyte capture chamber 31.

Preferably, the outer container 24 for the system is sealed to maintainsterility. To prevent pressure fluctuations from movement of liquid intoand from the system, a vent system 30 is provided in a wall of the outercontainer that permits movement of air out of the container when liquidis introduced and movement of air into the container when liquid isremoved. Details of suitable venting systems are described hereinafterwith respect to FIGS. 2B and 2C.

Referring to FIG. 2, the erythrocyte capture chamber 31 includes anouter wall 32, and an inner wall 34, the outer wall 32 having a top edge36 with an elevation higher than the top 8 of the inner wall 6. Thevertical distance between the top edge and the top of the inner wall issmall, preferably less than 1 mm, but large enough to allow passage ofcells, preferably greater than 50 microns. The narrow gap between thetop of the inner wall and the top of the chamber serves to minimize thesweeping of erythrocytes from the erythrocyte capture chamber into thecentrifugal drum by the swirling wave of PRP during deceleration aftercompletion of the centrifugation step. To further minimize sweeping oferythrocytes back into the centrifuge drum during deceleration, the gapabove the inner wall can be filled with a depth filter or screen. Thevolume of the erythrocyte capture chamber 31 is sized to retain thetotal volume of separated erythrocytes and leukocytes in the blood whileretaining a minimal volume of PRP. An annular cap 38 is secured to thetop of the centrifugal drum 5 and the erythrocyte capture chamber 31 ina sealing engagement that prevents escape of blood and blood productsfrom the centrifugal chamber during the centrifugal separation step.

The upper surface portion 42 of the inner wall 34 of the erythrocytecapture chamber 31 can optionally have a slope forming an angle “a” atleast 25° with the central axis, facilitating flow of platelets in thePRP flowing inwardly over the upper edge 8 of the erythrocyte capturechamber 31 when the erythrocytes sediment to fill the erythrocytecapture chamber 31.

FIG. 1 shows the separation system coupled with a syringe 44 positionedto introduce blood into the separation chamber 2. The syringe 44 isshown with the plunger or piston 46 in the extended, full position priorto the blood introduction.

FIG. 2A is a fragmentary cross-sectional drawing of an alternativeerythrocyte trap configuration. In this alternative embodiment, theupper surface portion 42 of the erythrocyte capture chamber 31 shown inFIG. 2 extends as surface 43 downward to the opposing wall 45, providinga continuous sloped surface for movement of platelets to the centrifugalchamber 5 during centrifugation. Surface 43 forms the angle “a” with thecentral axis (not shown) of the erythrocyte capture chamber.

FIG. 2B is a detailed fragmentary view of a vent system 30 a accordingto this invention that uses a sterile porous sheet to allow air movementinto and from the outer container. In this embodiment, an air flowpassageway 50 in a wall 52 of the outer container 24 (FIGS. 1 and 2) issealed with a conventional sterile porous sheet 54. The sterile poroussheet 54 that has sufficient porosity to allow free movement of airthrough the sheet, but is an effective microorganism barrier thatprevents movement of microorganisms from the outer environment into thecontainer 24. This prevents significant fluctuations of air pressure inthe outer container 24 during liquid movement into and out of thesystem.

FIG. 2C is a detailed fragmentary view of a vent system 30 b accordingto this invention that uses a flexible balloon or diaphragm to allow airmovement into and out of the outer container 24. In this embodiment, anair flow passageway 56 in the wall 52 of the outer container 24 (FIGS. 1and 2) is sealed with a balloon or flexible diaphragm 60. The balloon orflexible diaphragm 60 should have sufficient flexibility and size toallow free movement of air through the air flow passageway 56 in avolume that can be at least equal to the total volume of blood that isintroduced into the system during the separation process. This preventssignificant fluctuations of air pressure in the outer container 24during liquid movement into and out of the system. The balloon orflexible diaphragm 60 must have the integrity to be an effectivemicroorganism barrier preventing movement of microorganisms from theouter environment into the container 24 during PRP removal.

FIGS. 3-5 show successive stages in the preparation of PRP with thedevice of FIG. 1. FIG. 3 is a schematic cross-sectional drawing of thecentrifugal separator of FIG. 1 after being loaded with blood 62 fromsyringe 44. Syringe 44 is attached through the Luer port 28 andcommunicates with the access tube 29, and the plunger 46 has beendepressed to expel the blood contents of the syringe into the separationchamber 2.

FIG. 4 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 1 during the spin separation phase. During this phase,the syringe 44 can be removed as shown, to be replaced with a sterilecap or a fresh syringe to remove separated PRP product. Alternatively,the syringe 44 can be left in place during the separation phase (notshown) and reused to remove the PRP product. During the spin phase, thecentrifugal force causes the more dense erythrocytes 64 to move outwardthrough the plasma until they collect in the erythrocyte capturechamber, leaving PRP 66 in the centrifugal drum 5.

FIG. 5 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 1 after centrifugation has ended. When centrifugationis complete and the centrifugal forces are no longer present, the denseerythrocyte layer remains isolated in the erythrocyte capture chamber31, and the layer of PRP 66 in the centrifugal drum collects at thelowermost section of the centrifugal chamber. The PRP can then beremoved through the access tube 29 from the centrifugal drum 5 with theoriginal syringe 44 (FIG. 3) or a fresh syringe positioned as shown inFIG. 3.

If one desires to obtain a PRP concentrate according to this invention,one can use the concentrating syringe shown in FIG. 6 wherein FIG. 6 isa cross-sectional schematic view of a syringe embodiment for producingPRP concentrate from PRP. The syringe device 69 includes a processchamber 70 having an outer wall 72. In the process chamber 70, a plunger74 is positioned above filter 76, the plunger 74 and the filter 76defining a concentrating portion or chamber 78 of the process chamber70. The concentrator chamber 78 contains concentrating desiccatedhydrogel beads 80 and one or more agitators 82. A concentrate chamber84, positioned below or downstream of filter 76, includes aninlet/outlet port 86.

The concentrating desiccated hydrogel beads 80 can be insoluble beads ordisks that will absorb a substantial volume of water and not introduceany undesirable contaminant into the plasma. They can be dextranomer oracrylamide beads that are commercially available (Debrisan fromPharmacia and BIO-GEL P™ from Bio-Rad Laboratories, respectively).Alternatively, other concentrators can be used, such as SEPHADEX™moisture or water absorbents (available from Pharmacia), silica gel,zeolites, cross-linked agarose, etc., in the form of insoluble inertbeads.

The agitators 82 can be dense objects such as inert metal spheres. Itwill be readily apparent to a person skilled in the art that the shape,composition and density of the agitators 82 can vary widely withoutdeparting from the invention so long as the agitator has a densitysubstantially greater than whole blood. It is advantageous that theagitator be a metal sphere such as a titanium or stainless steel spherethat will not react with blood components, or a dense sphere coated withan inert coating that will not react with blood components.

The filter 76 can be any inert mesh or porous materials which willpermit the passage of plasma and prevent passage of the hydrogel beadsand agitator. The filter can be a metal wire or inert fiber frit ofeither woven or non-woven composition, or any other frit constructionwhich, when the liquid in the concentration chamber is passed throughthe filter, will permit passage of the PRP and not the hydrogel beadsand agitator, effectively separating the PRP from the hydrogel beads andagitators as will be described in greater detail hereinafter.

It is important that the water removal procedure be carried out withminimal activation of the platelets and minimal denaturation of thefibrinogen. Prior art commercial procedures for preparing plasmaconcentrate use precipitation to separate fibrinogen from albumin andreconstitution to prepare the sealant. This deactivates a major portionof the fibrinogen and removes healing factors. As a resultproportionally more of the reconstituted precipitate is required toachieve effective tissue sealing. With the device of this invention,denaturing of the fibrinogen is avoided by water removal and the healingfactors in the plasma are retained with the fibrinogen during theconcentration step, yielding a more effective tissue sealant andadhesive that also promotes healing.

FIGS. 7 and 8 show the preparation of PRP concentrate using the syringeconcentrator shown in FIG. 6. FIG. 7 is a schematic cross-sectionaldrawing of the centrifugal separator of FIG. 5 after PRP 66 has beendrawn into a concentrator syringe, and FIG. 8 shows a concentratorsyringe containing PRP concentrate 90 after the water removal phase.Moving plunger or piston 74 draws PRP 66 from the centrifugal drum 5into the syringe chamber. A volume of air is also drawn into the syringeto facilitate expulsion of PRP concentrate after concentration.

The concentrator syringe is then withdrawn from the centrifugalseparator and shaken by a reciprocal movement in the direction of thesyringe axis. This movement causes relative agitating movement of theagitator balls 82 in the PRP 66, stirring the hydrogel beads in thesolution, and mixing the PRP to reduce localized concentrations and gelpolarization of plasma proteins around the bead surfaces, therebyfacilitating movement of water from the PRP into the beads 80. FIG. 8shows the concentrator syringe with the PRP concentrate 90 after thewater removal step is completed. Movement of the plunger 74 toward theinlet-outlet port 86 discharges PRP concentrate 90 through theapplicator needle 92, the filter 76 preventing movement of the hydratedbeads 94 and agitator 82 with the PRP concentrate. Concentrated PRPretained within the interstitial space between beads is purged by air asthe plunger is depressed further.

FIG. 9 is a schematic cross-sectional drawing of a centrifugal separatorof this invention with a depth filter erythrocyte trap. This embodimentalso comprises a centrifugal separator unit 102 and a motor 104. Thecentrifugal separator unit comprises a centrifugal drum 106 having aninner wall surface 108 with a bottom edge 110, a drum bottom 112, and acentral axis (not shown). The drum bottom 112 has a central depression114, the bottom 112 constituting a floor sloping downward from the loweredge 110 to the central depression 114. The motor 104 has a drive axis116 coaxial with the central axis. The motor 104 has the capacity torotate the centrifugal drum 102 at a speed of at least 2,000 rpm for 120seconds with a total power consumption of less than 500 mAh, the powerthat is obtainable from a small battery such as a conventional 9 voltalkaline battery.

The complete, self-contained unit includes a battery 118 connected tothe motor 104 through conventional power connections. The battery 118has the capacity to provide sufficient power to complete the separationprocess and being connected to the motor through an on/off toggle ortimer switch 120 with a manual knob 122.

An outer container 124 encloses the centrifugal separation unit. Thecontainer 124 has a top 126 with a sterile syringe port 128 aligned withthe central depression 114, an access tube 130 connected to andextending downward from the syringe port 128 for introducing blood intothe separation chamber 132 and for removing PRP from the separationchamber 132 as is explained in greater detail with respect to FIGS.10-13 hereinafter.

The inner wall 108 of the centrifugal separator unit 102 is the surfaceof a depth filter 134 having pores sized to capture erythrocytes movinginto the pores during centrifugal separation of the erythrocytes fromblood and to retain the erythrocytes in the material of the depth filterwhen centrifugal separation is completed, the material of the depthfilter being selected from a material that does not significantlyactivate platelets contacting the surface thereof.

The depth filter 134 can be a honeycomb-like or woven fiber materialthat allows fluids and small particles to flow freely (e.g., felt oropen cell polyurethane foam). Like a wetted sponge, the depth filterholds liquid against a certain head of pressure due to surface tensionforces. Thus, blood cells or other suspended particulates remainentrapped within the foam when the centrifuge stops and separatedplatelet-rich plasma drains from the surface under the force of gravity.Foam can be either rigid or flexible and can be formed into theappropriate annular shape for the device by molding or die-cutting. Theparts are sized so that the packed cell (e.g., erythrocyte andleukocyte) layer is fully contained within the outer depth filterchamber, which retains the cells when the centrifuge stops.

With this device, erythrocytes moving outward through the plasma duringcentrifugation pass into and are captured by the depth filter 134, andthe PRP flowing downward when centrifugation is ended is substantiallyfree from erythrocytes as is described hereinafter in greater detailwith respect to FIGS. 10-13.

Similar to the vent system provided in the system shown in FIGS. 1 and2, a vent system 136 can be provided in the outer container 124. Thisvent system can be the same as described hereinabove with respect toFIGS. 2B and 2C.

FIG. 10 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 9 after being loaded with blood 138 from syringe 140,the syringe connecting through the sterile seal 128 and into thevertical tube 130, and the plunger 142 having been depressed to expelthe blood contents of the syringe into the separation chamber 132.

FIG. 11 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 10 during the spin separation phase. During thisphase, the syringe 140 can be removed as shown to be replaced with asterile cap or fresh syringe to remove the separated PRP product.Alternatively, the syringe 140 can be left in place (not shown) duringthe separation phase and used to remove the PRP product. During the spinphase, the centrifugal force causes the more dense erythrocytes to moveoutward through the plasma into the depth filter 134, leaving PRP 148substantially free from erythrocytes in the centrifugal drum 102.

FIG. 12 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 11 after centrifugation has ended. When centrifugationis complete and the centrifugal forces are no longer present, theerythrocyte-free PRP product 148 flows downward in the separator chamber132, the erythrocytes remaining trapped in the depth filter 134. The PRP148 that collects in the centrifugal drum 102 is substantially free fromerythrocytes and leukocytes. The PRP 148 can then be removed from thecentrifugal drum 102 with the original syringe 140 (FIG. 10) or a freshsyringe as will be readily apparent to a person skilled in the art.

FIG. 13 is a schematic cross-sectional drawing of the centrifugalseparator of FIG. 12 after PRP 148 has been drawn into a concentratorsyringe 69. Withdrawing the plunger or piston 74 draws PRP 148 from thecentrifugal chamber 132 into the syringe barrel 150.

The water is removed from the PRP 148 to produce a PRP concentrate andexpelled from the syringe as is described hereinabove with respect toFIGS. 7 and 8.

FIG. 14 is a schematic representation of a combination centrifugalseparator and hollow fiber concentrator of this invention. The entireseparation and concentration components are enclosed in a housing 160.The top of the housing has a sterile vent 162 to allow passage of airdisplaced during addition and removal of fluid from the device and aLuer fitting 164 to which a standard syringe 166 with a piston 168 andpiston actuator 170 can be coupled.

A centrifugal separator 172 can have the annular erythrocyte trappingsystem shown and described hereinabove with respect to FIGS. 1-5 or itcan have the depth filter erythrocyte trapping system shown anddescribed hereinabove with respect to FIGS. 9-13.

A drive motor 174 is positioned in the bottom section of the housing 160below the centrifugal separator 172 in the basic configurations shown inFIGS. 1 and 9.

Positioning the hollow fiber concentrator system 176 above thecentrifugal separator 172 simplifies the liquid transfer components ofthe concentrator, although it will be readily apparent to a personskilled in the art that alternative configurations such as side-by-sideplacement or placing the centrifuge above the concentrator are alsosuitable, provided adequate space is provided to house the fluidtransfer tubing.

The concentrator system comprises a hollow fiber cartridge 178 and apump 180.

A central tube 182 having outlet 184 extends from the Luer fitting 164toward the depression 186 at the bottom of the centrifugal separator172. A inlet flow check valve 188 limiting liquid flow toward thecentrifugal separator is placed in the central tube 182 at anintermediate level

The tube outlet 184 is positioned to circulate PRP, preferably stoppingshort of the bottom 186.

A return tube 190 extends from the bottom depression 186 to a pump inletcheck valve 192 communicating with the inlet of pump 180. Check valve192 directs liquid movement in the direction toward the pump, thuspreventing backflow into line 190. A second return tube, but alsoreferred to as a line or conduit, 194 extends from pump outlet checkvalve 196 communicating with the outlet of pump 180. Check valve 196directs liquid movement in the direction leading away from the pump,thus preventing backflow from line 194 to the pump. Second return tube194 extends to the inlet manifold 198 of the hollow fiber cartridgeconcentrator 178. A third return tube 200 extends from the outletmanifold 202 of the hollow fiber cartridge 178 to a concentrator outletcheck valve 204 leading to the central tube 182 at a position above (orupstream of) check valve 188. Tube 200 is sized to restrict the flow offluid, generating a backpressure upstream in the fluid circulation pathto drive filtration through the hollow fiber membranes. Check valve 204prevents backflow of liquid from the tube 182 to the hollow fibercartridge 178.

The hollow fiber cartridge includes fiber membranes that efficientlyremove water and salts from the plasma while leaving larger healingfactors. Choice of the fiber materials and pore distributions is acritical factor because rapid water removal without significant plateletdamage must be achieved. The large concentration of protein present inplasma presents another difficulty since it thickens along the membranesurface due to localized concentration and gel polarization. Therefore,the fiber membranes and their configuration must facilitate sweeping ofthe membrane surface by passing plasma, disrupting the polarization andredistributing the plasma constituents. Furthermore, because a preferredembodiment of this device is intended to be self-contained and highlyportable, it is preferred that the hollow fiber cartridge provide itsultrafiltration function with minimal energy consumption so thatcomplete separation and concentration can be achieved with a standardsmall (e.g., 9 volt transistor) battery.

The pump 180 can be a conventional piston or diaphragm pump thatprovides the necessary circulation of plasma through the hollow fiberconcentrator system 176 without use of excessive energy. Preferably, thepump 180 should have the capacity to complete concentration of theplasma with a power consumption of less than 500 mAh, that is, the poweravailable from a small battery such as a standard 9 volt alkalinebattery.

Power to the motor 174 and pump 180 is provided by conventional wiringand a small battery (not shown) that has the capacity to providesufficient power to complete the concentration process. A small (e.g.,standard 9 V transistor radio) battery is acceptable. Alternatively, ifthe unit is to be used in a location with standard auxiliary power, aconventional power supply system using standard business and residentialpower can be used.

The system shown in FIG. 14 operates as follows: Blood is provided toseparator Luer fitting by a blood-filled syringe, using syringe such assyringe 166. Downward movement of the actuator 170 moves the piston 168in a downward direction, expelling the contents of the syringe throughthe Luer fitting 164 and the tubing 182 through the inlet check valve188 into the bottom of the centrifugal separator 172. After its contentshave been expelled, the syringe can be left in place or replaced with afresh syringe or sealing cap to prevent fluid from escaping through theLuer port 164 during the concentrating step of the process.

Operation of the centrifugal separator 172 removes erythrocytes andleukocytes from the blood, leaving PRP in the bottom of the centrifugechamber after centrifugation is stopped.

Operation of the pump 180 draws PRP from the lower depression 186 of thecentrifugal separator upward through tube 190, through the pump inletcheck valve 192 into the pumping chamber (not shown) of the pump 180.Then PRP flows through pump 180 and through pump outlet check valve 196.From check valve 196, the PRP passes through the tubing 194 into theinlet manifold 198 of the hollow fiber concentrator 178 and through thehollow fiber concentrator.

PRP from which a portion of the water and salts have been removed thenflows from the outlet manifold 202 of the hollow fiber concentrator 178through flow restrictive tubing 200 and concentrator outlet check valve204 to the inlet tubing 182, and then through check valve 188 to thebottom of the centrifugal separator 172 where it mixes with the otherPRP. This cycling process is continued, removing a portion of the waterin each pass, until the desired concentration of PRP has been obtained.

With the device of this invention PRP erythrocyte removal andconcentration of the PRP to a platelet concentration of 3× can beautomatically achieved within 5 minutes. If higher PRP concentration isneeded for a particular application such as for sealing tissues to stopbleeding, the concentration cycle can be continued beyond 5 minutes,whereby concentration up to 5× and higher can be achieved.

FIG. 15 is a schematic cross-sectional view of a hollow fiberconcentrator shown in FIG. 14, and FIG. 16 is a cross-sectional view ofthe hollow fiber concentrator of FIG. 15, taken along the line 16-16.

Referring to FIG. 15, the hollow fiber concentrator 178 is combined withan extracted liquid reservoir 206. The concentrator 178 has an outerhousing 208 that encloses the inlet manifold 198, an outlet manifold202, a plurality of hollow ultrafiltration fibers 210 and an extractedliquid chamber 212. Each of the hollow fibers 210 has a wall 214, anaxial passageway 216, an inlet end 218 and an outlet end 220. The inletend 218 of each hollow fiber 210 is secured to a correspondingly sizedhole in the inlet manifold plate 222 in a conventional manner thatestablishes communication between the hollow fiber passageway 216 andthe inlet manifold 198 while preventing escape of the liquid contentsthereof into the extracted liquid chamber 212. The outlet end 220 ofeach hollow fiber 210 is secured to a correspondingly sized hole in theoutlet manifold plate 226 in a conventional manner that establishescommunication between the hollow fiber passageway 216 and the outletmanifold 202 while preventing escape of the liquid contents thereof intothe extracted liquid chamber 212.

Referring to FIGS. 15 and 16, the extracted liquid chamber 212 is thespace defined by the inner wall surface 213 of the housing 208, theouter wall surface of the hollow fibers 210, and the manifold plates 222and 226. The extracted liquid chamber 212 captures the liquid thatpasses through the hollow fibers 210 in the ultrafiltration process.

The outlet end of conduit 194 shown in FIG. 14 connects with the inletmanifold 232 through manifold inlet conduit 230. The inlet end ofconduit 200 shown in FIG. 14 connects with the outlet manifold 202through manifold outlet conduit 228.

During the water removal process, pressurized plasma passes from conduit194 through the inlet manifold inlet conduit 230 into the inlet manifold198, and then through the hollow fibers 210. In each pass a portion ofthe water and salts passes through the pores in the fiber walls into theextracted liquid chamber 212. The concentrated plasma then passes intothe outlet manifold 202, through the outlet manifold outlet conduit 228and then to the conduit 200.

The extracted liquid reservoir 206 has a reservoir housing 234 thatconnects with an overflow conduit 236. The overflow reservoir 206 has anair vent 238.

FIG. 17 is a schematic cross-sectional view of the membrane valve airvent 238 in the hollow fiber concentrator of FIG. 15. The valve 238comprises a porous lower hydrophilic membrane 240 communicating with theinterior of the extracted liquid reservoir 206 and a porous upperhydrophobic membrane 242 that communicates with outer space surroundingthe reservoir. The extracted liquid reservoir captures extracted liquidwhen the volume of the extracted liquid exceeds the volume of theextracted liquid chamber 213 and the excess liquid escapes through theextracted liquid conduit 236 into the extracted liquid chamber 206. Airin the extracted liquid chamber displaced by the incoming liquid escapesthrough the porous membranes 240 and 242 until the liquid level reachesthe membranes, saturating the hydrophilic membrane 140. Escape of theextracted liquid from the extracted liquid chamber 206 is prevented bythe hydrophobic membrane 242.

The valve prevents movement of air into the system when PRP concentrateis removed as follows. Movement of PRP concentrate from the centrifugalseparator 172 (FIG. 14) creates a partial vacuum in the system. Movementof air through the valve 238 in response to this partial vacuum isprevented by the liquid saturated hydrophilic membrane 240.

FIG. 18 is a schematic cross-sectional drawing of an automatedspring-clutch system for preparing PRP concentrate from a patient'sblood. Like other embodiments of this invention, the disposable,single-use system is enclosed in a compact portable device that can besmaller than a twelve ounce soft drink can.

Referring to FIG. 18, the outer housing 252 is sealed except for theblood inlet port 254, the PRP concentrate withdrawal port 256, andsterile vent 258. The PRP withdrawal port 256 is one end of a rigid PRPconcentrate withdrawal tube 260 that is secured to the outer housing 252and functions as a central axle around which the rotary separationcomponents turn and also as a PRP concentrate withdrawal tube. Theseparation components comprise a upper rotary centrifugal separatorhousing 262 and a lower rotary water removal system housing 264, thesetwo housing being connected by an integral cylindrical waist element 266into a unitary housing structure. The water removal system housing 264includes a PRP concentrate reservoir 268 that communicates with thelower opening 270 of the PRP concentrate withdrawal tube 260.

The rotary components are supported on the drive axle 272 of the twodirection, two speed motor 274. The direction and speed of the motor 274are controlled by the conventional motor controller 276 to which it isconnected by electrical conduit 278. Switch 280 activates the motorcontroller 276.

The relative position of the rotary components in the outer housing 252is maintained by a roller bearing raceway structure. This structure thatincludes a plurality of roller bearings 282 positioned between an outerring flange 284 secured to the outer housing 252 and an inner ringflange 286 secured to the upper rotary centrifugal separator housing262.

The centrifugal blood separating components housed in the upper housing262 of the rotary assemblage is similar in structure and function toother blood separators described hereinabove with respect to FIGS. 9-13in that the cylindrical rotary centrifugal separator 290 has the innersurface of its outer wall lined with a cylindrical depth filter 294. Ablood overflow reservoir 296, defined by a floor 298 and an integralwall 300, can function to control or limit the volume of blood that issubject to the separating operation. The overflow reservoir 296 canassist if the volume introduced exceeds the volume that can beeffectively concentrated in the water removal operation, described ingreater detail hereinafter. When the centrifugal separator spins duringthe separation phase, excess blood flows upwardly along the wall 300 andinto the reservoir 296. When the separation phase ends and the rotaryspeed slows, the wall 300 prevents escape of liquid as it settles on thefloor 298.

Suitable depth filter materials have been described hereinabove withrespect to FIGS. 9-13. Alternatively, the depth filter structure 294 andoverflow reservoir structure 296 can be replaced with an erythrocytetrap and function such as is described with respect to FIGS. 1-8hereinabove in a manner that would be readily apparent to a personskilled in the art.

During the centrifugal separation stage, erythrocytes separating fromthe plasma flow into the depth filter 294, leaving a layer of PRP behindoutside the depth filter.

When the centrifugal separation is completed and centrifugal separationis ended, the PRP flows to the bottom of the centrifugal separator whereit is held by the seal of the valve plate 302 against the floor 304 ofthe separation housing.

The seal of the valve plate 302 against the floor 304 is opened byaction of a spring clutch assembly. The valve plate 302 is a part of avalve assembly including a hollow upper valve stem 306 (a cylinder)integral with the plate 302 through which the rigid tube 260 extends.This stabilizes orientation of the valve assembly on the rigid tube 260.The lower part of the valve assembly is outer cylinder 308 with internalthreads 310.

The outer cylinder 308 further encloses an inner cylinder 312 that hasexternal threads 314 engaging the internal threads 310 of the outercylinder 308 in sliding engagement. The spring clutch 288 wraps aroundthe rigid tube 260 and is positioned between the inner cylinder 312 towhich it is secured and the rigid tube 260. The spring clutch 288functions as a slip bearing between the rotating internal threadedelement 312 and the rigid tube 260 during the centrifugal separationphase because the direction of the movement of the spring around therigid tube 260 tends to open the spring, reducing then sliding friction.

After the centrifugal separation of the PRP is completed, the motor 274is then activated to turn slowly in a reverse direction. Thespring-clutch 288 rotates around the rigid tube 260 in a direction thattightens the spring, locking the spring to the rigid tube 260. As theouter cylinder 308 turns around the locked stationary inner cylinder312, the outer cylinder 308 rises, lifting unseating the valve plate306, the movement continuing until the top surface 316 of the uppervalve stem 306 abuts the collar 318 secured to the rigid tube 260.

When the valve plate 302 unseats, the PRP in the bottom of thecentrifugal separator 290 flows downward through a channel 320 definedby the outer surface 322 of the lower cylinder and the inner surface 324of the waist cylinder 266 into the lower rotary water removal systemenclosed in the lower housing 264 where it contacts the desiccated gelbeads 326. Direct flow of liquid from the water removal system isprevented by O-ring seal 327.

The lower rotary water removal system 328 enclosed in lower housing 264comprises a rotary cylindrical screen element 330 which has radiallyinwardly extending comb elements 332 and a rake system. The bottom ofthe lower housing 264 has a central opening with a downwardly extendingcylindrical flange 333 to accommodate the rigid tube 260. O-ring 327 ispositioned between flange 333 and the rigid tube 260 to prevent liquidflow therebetween. The rake system comprises a rake cylinder 334 havingradially outward extending rake elements 336 that mesh with the combelements 332. The rake cylinder 334 is separated from the rigid tube 260by roller bearings 338 that reduce friction between the rake cylinder334 and the tube 260 during the high speed rotation of thecentrifugation step. The rake cylinder has a projecting spline 340 thatengages a matching vertical recess grove (now shown) in the lower valvestem outer cylinder 308. The spline 340 is positioned to move up anddown in the matching grove to maintain engagement of the rake cylinder334 and the lower valve stem outer cylinder 308 at all elevations of thevalve stem. The spline system locks the rake cylinder 334 to thestationary tube 260 when the spring clutch engages, preventing rotationof the rake cylinder when the comb elements are rotated through therakes.

As water is removed from the PRP by the desiccated beads 326, gelpolarization occurs, slowing water absorption into the beads. To reversethis effect, the beads are slowly stirred during the dewatering processfrom slow rotation of the cylindrical screen and rake elements by themotor 274. The relative movement of the rake 336 through the gel beads326 and through the spaces of the comb 320 stirs the beads and breaks upbead clumps, increasing efficiency of the water removal process. Thisprocess is obtained as follows.

When water removal is completed, the motor controller 276 can reverserotational direction of the drive shaft 272, causing disengagement ofthe spring clutch 288 from the rigid tube 260, and permitting theseparation assembly elements to rapidly spin as a unit. During thisspin, the concentrated PRP is spun from the beads 270 through thecylindrical screen 330 where it is collected in the PRP concentratereservoir 268. PRP concentrate is then drawn from the PRP concentratereservoir 268 though the rigid tube 260 and out through the PRPconcentrate withdrawal port 256.

FIG. 19 is an isometric view of a plasma separator and concentratorembodiment of this invention; and FIG. 20 is a top view of the plasmaseparator and concentrator shown in FIG. 19. This embodiment comprises adisposable separator/concentrator module 350 and a permanent base 352with the motor and control system. The separator/concentrator module 350has a housing 354 and a housing top 356. The housing top 356 has a bloodinlet port 358 and a plasma concentrate outlet port 360. The base 352has a base housing 362 with a control switch 364 and an external powerconnector 366 (FIG. 20). This compact unit separates platelet richplasma (PRP) from blood and removes water from the PRP to form anautologous platelet rich plasma concentrate from a patients blood withinminutes.

FIG. 21 is a cross-sectional view of the plasma separator andconcentrator of FIG. 20, taken along the line 21-21, separated along thevertical axis to show the motor drive and drive receptor relationshipprior to placing the disposable separator-concentrator assembly on thedrive base. The drive base 368 comprises a base housing 370 supported ona plurality of base feet 372. The housing has a rotary assembly guidesurface 374 that is shaped to match the shape of the base receptor 376of the separator and concentrator assembly 350. It has an annularsupport surface 380 that together with the top support surface 382supports and aligns the separator and concentrator assembly 350 on thebase 368. In the base 368, a motor 384 is mounted on a support plate 386that is held in position by a plurality of support fixtures 388. Themotor 384 has a drive connector 390 that securely mates with the rotaryassembly drive receptor 392. The base has a conventional power connector366 and a conventional motor control switch 364 that are electricallyconnected to the motor with conductors in a conventional manner (notshown). The motor control switch 364 includes a conventional timer thatcontrols the motor speed at different phases of the separation andconcentration process as is described in greater detail hereinafter.

The rotary unit comprises the housing 354 with the housing top 356supporting the PRP concentrate outlet port 360. The housing 354 includesa base 394 with a base receptor 376 that is shaped and sized to matewith the top support surface 374 and assembly guide to support and alignthe separator and concentrator assembly 350 on the base 374. Axiallyconcentric bearing assembly 396 is positioned to support the separatorand concentrator assembly 350 in position to permit mating of the driveconnector 390 and the drive receptor 392. The drive connector 390 anddrive receptor 392 have matching shapes that require the two units toturn a single unit. They can have any cross-sectional shape thatprevents the drive connector 390 from turning inside the drive receptor392 such as the rectangular shape shown. It can also have any otherpolygonal or oval shape that provides this result. Circularcross-sections are also acceptable if they are keyed in a conventionalmanner fully within the skill of the art, and all functionallyequivalent shapes are intended to be within the scope of this invention.

The separation and concentration assembly 378 rotates about the verticalaxes established by the stationary fixed tube 398. Tube 398 alsoconstitutes a PRP concentrate conduit. This communicates with the PRPconcentrate outlet 360. Tube 398 is rigidly secured against rotationabout its central axis by its connection with the top 356 of the outerhousing 354. The lower end 398 of the tube 398 includes a PRPconcentrate inlet 400 and a rake hub 402 that is rigidly connected tothe tube so that it remains stationary when the rotary components are inmotion as will be described in greater detail hereinafter.

The separation and concentration assembly 378 includes a rotary housing378, the tapered bottom 404 of which includes the drive receptor 392.The separation and concentration assembly 378 has a top plate 406 with asterile vent 408 that is supported in its position on the tube 398 bysleeve bearing 410.

The desiccated gel beads used to removed water from the PRP are omittedfrom FIGS. 21-23 to present more clearly the other components of theconcentrating assembly. They are shown in FIGS. 24-27.

The separation and concentration assembly 378 has an outer wall 412 thatisolates the blood components during the separation and concentratingprocess. The upper portion of the housing 378 encloses a centrifugalplasma separator that comprises a cylindrical blood reservoir 416 withan outwardly tapering inner surface 418 and an inner wall 420 thatsurrounds the tube 398 and is configured to permit free rotation of theinner wall 420 around the tube 398. This combination maintains axialorientation of the blood reservoir during centrifugal motion of theseparation process. Surrounding the blood reservoir 416 is a cylindricaldepth filter 424 above which is positioned an annular blood overflowreservoir 426, details and functions of which are described in greaterdetail hereinbelow with respect to FIG. 23.

A concentrator assembly 428 is positioned below the blood reservoir 416and depth filter 424. The concentration assembly comprises aconcentrating basket 429 formed by an axially concentric rotary screen430 and a concentrator base 432. The screen has a cylindricalcross-section and is supported by a circular array of vertical supports434. Surrounding the screen 430 is a concentric PRP concentratereservoir comprising a vertical side wall 438 and the tapered bottom404. The center of the tapered bottom 404 is positioned adjacent theinlet opening 400 of the tube 398.

FIG. 22 is a cross-sectional view of the plasma separator andconcentrator of FIG. 20, taken along the line 22-22 and should beconsidered together with FIGS. 21 and 23 to form a completeunderstanding of the structure of the invention. The view provided bythis figure shows, in addition to features described above with respectto FIG. 21, a cross-sectional view of the blood inlet 358 supported bythe housing top 356 and the rake elements 440 mounted on the rake hub402.

FIG. 23 is a fragmentary cross-sectional view of theseparator-concentrator shown in FIG. 22. A top plate 442 is secured tothe top of the outer wall 412 to confine the blood to the separatorduring the centrifugal separation. The top plate 442 supports a blooddistribution tube 444 that is positioned below and in alignment with theblood inlet port 358 at the first stage when blood is introduced intothe separator.

The annular blood overflow chamber 426 has a top plate 446 with a bloodflow inlet opening 448 adjacent the top plate 442 and a second ventopening 450 that is radially inward from the blood inlet opening. Thisallows overflowing blood to enter the chamber during the centrifugalseparation phase through the first inlet opening 448 and allows escapeof air displaced by the blood through the second vent opening 450.

The tapered outer wall 418 of the blood reservoir has a tip edge 449.

A PRP flow passageway 451 leads from the outer separation chamber 453 tothe concentrator basket 429.

The rakes 440 have a terminal tip edge 452 that are positioned adjacentthe inner surfaces 454 of the upright screen supports 434 so theyclosely sweep the surfaces 454 during their rotation. The upright screensupports 434 have a thickness and openings 456 into which gel beadscollect during the fast centrifuge phase, placing them beyond the tipedge of the rakes.

The screen 430 has a mesh size that is sufficiently small to preventescape of the gel beads from the chamber concentration chamber duringthe final centrifugal separation of the PRP concentrate from the gelbeads.

FIGS. 24-27 illustrate the device of FIGS. 19-23 during the phases ofthe blood separation and concentration. FIG. 24 is a cross-sectionaldrawing of the device of FIGS. 19-23 after blood has been added, FIG. 25is a cross-sectional drawing of the device during the centrifugalseparation stage producing PRP, FIG. 26 is a cross-sectional drawing ofthe device during the slow rotation concentration stage, and FIG. 27 isa cross-sectional drawing of the device of during the centrifugal PRPconcentrate separation stage.

The blood separation and concentration with the device of this inventionproceeds as follows:

Referring to FIG. 24, a quantity of blood 458 that approximates thevolume that can be concentrated (dewatered) by the gel beads isintroduced into the blood reservoir 416 through the inlet opening 442and distribution tube 444. The blood 458 can be introduced through theneedle of the original sample syringe or another device. The blood isshown after is has settled in the bottom of the blood reservoir 416.

In FIG. 25, the motor 384 is energized to rotate the separator andconcentrator assembly 378 at a fast spin rate that effects centrifugalseparation of the more dense erythrocytes in the blood from the PRP. Thecentral tube 360 and attached rake 440 remain stationary during thisrapid rotation, and the gel beads 460 are spun by the rotary componentsand held by the centrifugal force against the screen 430, beyond thereach of the tips 452 of the stationary rake tips 440. The centrifugalforce causes the blood 458 to flow up the tapered inside wall 418 of theblood reservoir 416 and over the tip edge 449, to collect against thedepth filter 424 as shown in FIG. 25. The separation is achieved as afunction of cell density, sending the most dense erythrocytes outwardand through the passageways of the depth filter 424. The plateletsremain in the PRP layer 462 that forms against the depth filter 424.

After separation of the cells is complete, the rotation of the separatorand concentrator assembly 378 is slowed. PRP flow passageways 451 leadfrom the outer separator chamber 453 to the concentrator basket 429. ThePRP 462 flows from the pores and surface of the depth filter 424downward through the PRP flow passageway 451 into the concentratingbasket 429. Erythrocytes remain trapped in the pores and passageways ofthe depth filter 424 so that the PRP 463 reaching the basket 429 issubstantially free of erythrocytes.

As shown in FIG. 26, the PRP 463 flows into contact with the desiccatedgel beads 460 that have collected on the base 432 of the concentratingbasket 429. As the beads absorb water from the PRP, they swell, and thePRP immediately adjacent the bead surface thickens and becomes tacky.The continuing slow movement of the concentration basket 429 past thestationary rake 440 and the vertical supports 434 stirs the beads 460,reducing gel polarization on the bead surface, and breaking up the beadclumps. This slow stirring movement of the rotary components iscontinued until the water removal stage is completed.

The motor speed is then increased to a fast spin mode, and thecentrifugal force moves the gel beads 460 to the surface of the screen430. The centrifugal force generated by the spin caused the PRPconcentrate 464 to flow away from the surfaces of the beads and throughthe screen 430 to collect the PRP concentrate in the PRP reservoir asshown in FIG. 27. The PRP concentrate is removed with a syringe throughtube 398 and PRP outlet port 360.

FIG. 28 is a cross-sectional view of a portable embodiment of thisinvention. This embodiment includes a blood separation and concentrationsystem in the upper housing 354 that is identical to the bloodseparation and concentration system described with respect to FIGS.19-23. Because these components are identical and to avoid unnecessaryredundancy, no separate description of the identical components isprovided herein, the description of these elements with respect to FIGS.19-27 being incorporated by reference. For details about the bloodseparation and concentration systems, see the description of thecomponents provided hereinabove with respect to FIGS. 19-23.

The system shown in FIGS. 19-23 comprises a disposable blood separationand concentration unit and a permanent motor control unit. This assemblyis optimum of use in a laboratory or surgical setting found in ahospital or medical clinic.

For applications where a permanent motor and control system powered fromconventional power sources is not practical, a portable fully integratedembodiment of this invention is provided. The major difference betweenthe embodiment shown in FIG. 24 is the integration of the motor, powersupply and control system in a unitary system with the blood separationand concentration system. The lower casing or housing 470 encloses themotor 472, power supply 474 and control system 476. The motor 472 issecured to a motor support plate 478 mounted on the motor supportsuspension 480. The motor support suspension 480 is secured the lowersurface 482 of the base 484 in a position to maintain axial alignment ofthe motor with the axis of the rotary elements of the separator andconcentrator unit. The motor drive shaft is secured to the separator andconcentrator assembly by a coupling 485. The motor 472 is connected tothe battery power supply 474 and control system 476 with conventionalelectrical circuitry (not shown). The battery power supply iselectrically connected to the control system 476 with conventionalelectrical connections 486. A conventional removable plate 487 can beremovably secured to the lower portion of the lower housing 489 in aposition that permits insertion of the power supply battery 474 when itis removed. This allows insertion of an active battery immediatelybefore deployment or use of the system.

The control system 476 is a conventional motor controller and timer thatestablishes and controls the motor speeds during the rapid rotationcentrifugation phases of the blood separation and during theconcentration stages, and during the slow rotation concentration stage.These stages are the same as are described hereinabove with respect toFIGS. 24-27.

The weight and size of the separator and concentrator elements areselected to conserve energy and to be fully operational with a standard9 volt battery. This enables the device to be a completely portablesystem that does not require external power. It is thus suitable for usein mobile field units and field hospitals where self-powered, fullyportable units are needed.

The operation of the embodiment shown in FIG. 28 is the same as isdescribed above with respect to FIGS. 24-27.

1. A PRP separator and concentrator having a central axis comprising astationary housing and a rotary assembly mounted for rotation in thestationary housing about the central axis, with respect to thestationary housing, the rotatable assembly comprising a rotatablecentrifugal separator and concentrator, a drive motor, and a couplingconnecting the drive motor and the rotatable assembly, the motor anddrive coupling being positioned to rotate the rotatable assembly aboutthe central axis, the centrifugal separator having an inner separationchamber and an outer erythrocyte capture system, the concentratorcomprising a concentration chamber containing desiccated beads, theconcentration chamber having a floor and a plurality of upright screensupports, the upright screen supports having an inner surface and anouter surface, a cylindrical screen supported on the outer surface ofthe upright screen supports, an axially concentric stationary tubesecured to the housing and extending through the concentration chamberwith a stationary bead rake secured to the stationary tube and extendingradially outward, the rake having a distal edge that is positionedadjacent the inner surface of the upright screen supports, whereby slowrotation of the rotary assembly with respect to the stationary housingpulls the beads past the stationary rake, reducing gel polarization andclumping of the beads.
 2. The separator and concentrator of claim 1wherein each pair of adjacent upright screen supports defines adesiccating bead receptor for holding desiccated beads radially outwardfrom the distal edge of the rake, whereby bead disruption by the rakeduring high speed rotational phases is substantially avoided.
 3. Theseparator and concentrator of claim 2 including a motor controller,wherein the drive motor has a high rotational speed required forcentrifugal erythrocyte separation and PRP collection phases and a slowrotational speed required for water removal by desiccated beads, themotor controller include a switch for initiating high and low rotationalspeeds of the rotary assembly.
 4. The separator and concentrator ofclaim 3 wherein the switch initiates high rotational speed of the rotaryassembly during centrifugal and PRP concentrate collection phases andinitiates low slow rotational speed of the rotary assembly during thePRP concentrate collection phase.
 5. A rotatable PRP concentrator havinga stationary housing with a central axis, the concentrator including adrive motor and a rotatable centrifugal PRP concentrate separator, acoupling connecting the drive motor and centrifugal PRP separator forrotation about its central axis, the PRP separator including aconcentration chamber containing desiccated beads, the concentrationchamber comprising a floor and a plurality of upright screen supports,the upright screen supports having an inner surface and an outersurface, a cylindrical screen supported on the outer surface of theupright screen supports, an axially concentric stationary tube securedto the housing and extending through the concentration chamber, astationary bead rake secured to the tube and extending radially outwardto adjacent the inner surface of the upright screen supports, wherebyslow rotation of the rotary assembly with respect to the stationaryhousing pulls the beads past the stationary rake, reducing gelpolarization and clumping of the beads.
 6. The concentrator of claim 5wherein each pair of adjacent upright screen supports and the screensegment extending therebetween defines a desiccating bead receptor forholding desiccated beads radially outward from the distal edge of therake during high speed rotation, whereby bead disruption by the rakeduring high speed rotational phases is substantially avoided.
 7. Theconcentrator of claim 5 including a motor controller, wherein the drivemotor has a high rotational speed required for the PRP collection phaseand a slow rotational speed required for water removal by desiccatedbeads, the motor controller include a switch for initiating high and lowrotational speeds of the rotary assembly.
 8. The concentrator of claim 7wherein the switch initiates high rotational speed of the rotaryassembly during the PRP concentrate collection phase and initiates lowslow rotational speed of the rotary assembly during the PRP concentratecollection phase.